The present invention relates to a spacer arrangement with fusable connector for insulating glass units.
In the field of insulating glass units (hereinafter IG units), the use of a tubular spacer bar to separate panes of glass forming an IG unit, has been around the window industry for many years. It has been common practice, when fabricating a rectangular IG unit, to cut the spacer bar into specific lengths and connect the four spacer pieces with some sort of connector device or corner key to form the corners of the spacer bar arrangement (frame) of the IG unit. The device used to connect the spacer pieces to form a corner, which could be a square corner or some other angled corner, is called a corner key. In order to conserve spacer material, miscellaneous lengths of spacer bar are often connected with a linear spacer key arrangement. The design of the corner key and its material selection has varied over the years. Typically, the corner key is a stamped metal part, a cast alloy piece or an injected molded plastic material. Other materials have been tried, but these are the most common material selections. With regard to corner key design, the shape and/or cross section has varied greatly with each designer searching for the optimum ease of insertion and resistance to pull-out. Also some spacer keys are designed to allow desiccant pass through, and others have been designed for ease of mechanically crimping the spacer to the key. Also used was high temperature welding for a steel spacer corner section.
Understandably, spacer connectors are an important component of the IG unit. They serve as a mechanical connection between the linear spacer pieces so that a functional tubular spacer or glass separator is formed to be used as an integral part of the finished IG unit. Typically, after the spacer bar pieces are connected to form a closed rectangular frame, sealant is used to bond the desiccant-filled spacer to the glass surface. Variations in the IG unit assembly process have been developed in the fenestration industry's search for the most cost effective IG manufacturing process. For example, a folding corner key was developed so that the spacer forming process could be a linear process. Also, the technology of “corner bending” was developed to eliminate the corner key, but in this case, a linear key is usually still required to complete the spacer frame. In addition, the Intercept IG technology on in-line spacer manufacturing has made the economics of spacer fabrications quite cost effective. Most of this spacer technology has been developed over the last seventy years, and the search continues to continually improve the spacer manufacturing process.
The TGI spacer from Technoform as described in US 2005/0100691 A1 or EP 1 529 920 A2 is a plastic metal composite spacer, where the inside of the spacer profile is made of plastic.
A conventional metal spacer, as shown in U.S. Pat. No. 6,339,909, can be made of metal such as aluminum or stainless steel or the like such that the inside of the spacer profile is made of metal.
The connectors or keys have been metal or nylon-like pieces with barbed teeth designed for easy insertion and difficult extraction or pull-out. Both corner keys and linear keys are available. These connectors seem to work reasonably well, but they are expensive per piece and several pieces may be needed for each spacer frame. Also, they can be ineffective in holding the spacer pieces together under specific conditions/circumstances, and they can be difficult to insert because the gripping teeth must be pushed into or along the interior surface of the spacer cross section.
This invention should overcome at least some of the short comings encountered with the use of conventional spacer connectors.
As mentioned, the spacers may have a metal inside surface or a plastic inside surface. It is proposed that a spacer connector be utilized that    (1) has a shape and size tolerances for easy insertion into the spacer cavity,    (2) is composed of a low cost plastic, in one embodiment similar to the TGI spacer interior lining, and    (3) is fused to the interior surface of the spacer cross section.
This last feature (3) has particular significance because it is a unique concept of bonding the connector to the spacer for superior bond strength and convenience. Significantly, this proposal entails a relatively low temperature fusable process, that is, with a temperature range from room temperature to about 600° F. (approx. 315° C.). Fusing in this sense encompasses, in case of a spacer having a plastic inside surface, fusing by creating a material connection by melting of the inside plastic surfaces of the spacer and the outer plastic surface of the connector such that the molten materials mix and have an irreversible material connection after cooling down as well as, in case of a spacer having a metal inside surface, a strong adherence created by melting the outer plastic surface of the connector such that a strong adhesion and/or bond to the inside metal surface of the spacer is present after cooling down.
Often times, the conventional spacer key will work loose from its mechanical connection, allowing the spacer pieces to separate from each other.
This results in a failed IG unit because of moisture penetration at the open joint. With the proposed bonding, the spacer joint is fused together, and it performs as strong welded joint which prevents joint opening.
That means, it is proposed that a low cost connector be utilized as a “bonding component” for IG spacers.
There are several methods of creating this fused connection between the key, such as a corner key or a linear key, and the spacer.
A few methods are suggested in the following, and of course, the following listing is not intended to be all inclusive:    (1) Direct application of heat via conductive heat to fuse a thermoplastic connector and the thermoplastic or metal spacer liner. This conductive heat could be applied with direct contact between the heater and the joint area.    (2) Use of radiation heat from a flame or IR lamp to heat the joint.    (3) Use of hot air heating from an intense hair drier-like device.    (4) Use of friction welding, since welding equipment is available that will rapidly move the joint parts relative to each other causing friction heat that induces a fused joint.    (5) Use of ultrasonic or RF (including microwave) welding, whereby the material molecules are vibrated and this motion generates heat, and the heat causes the materials to soften and bond together.    (6) Use of chemicals on the surface of the components that cause the surfaces to fuse together. The connecting of plastic pipes is an example of this method.    (7) Use of an adhesive, glue or sealant to accomplish the desired joint.
These are just a few examples of the possible methods of fusing the spacer connectors to the spacer bars. In summary, the use of a low temperature, fused spacer connection is a unique approach to solving the problems or shortcomings of the present day connectors.